Piston of uniflow steam-engines



H. FILLING.

PISTON 0F UNIFLOW STEAM ENGINES. APPLICATIUNFILEU 1AN.6',1921.

1,385,226. Patented July 19, 1921.

2 SHEETS-SHEET 2.

PATENT' OFFICE.

HENRY FILLING, OF CHORLTON-CUM-HARDY, ENGLAND.

PISTON OF 'UNIFLGW STEAM-ENGINES.

Application filed January 6, 1921.

T 0 all whom it may concern:

Be it known that I, HENRY PILLXNG, a subject of the King of Great Britain, residing in Chorlton-cum-Hardy, England, have invented certain new and useful Improve ments Relating to Pistons of Uniflow Steam-Engines, of which the following is a specification.

This invention relates to pistons of unifiow steam cylinders and more particularly to the means for supporting the weight oit the pistons.

In a large horizontal cylinder, if the weight of the piston is taken up by iront and rear guides, difficulties are liable to arise Jfrom the deflection of the piston rod and if the weight is carried by the bottom of the cylinder it is essential that the rubbing surfaces should be always in perfect contact and that the pressure should be equally distributed over these surfaces.

This condition is not easily fulfilled, owing to the varying temperatures to which the cylinder is exposed, which temperature is a minimum at the center where the steam is exhausted and a maximum at the end where the steam is admitted.

The difficulty is also enhanced by the varying temperatures to which the piston is exposed, which produce alterations in the diameter of the piston and in the axial len h of the piston and piston rod.

he piston is of the type comprising two separate and independent working parts connected by a central piston rod and according to the invention these separate parts are held against collars on the piston rod by nuts, cotters or the like which are relieved from the pressure due to the steam load.

Also, the weight of the pistons is supported by a slipper or chair itted between the two separate parts of which the piston `is composed. The chair may in small pistons be a solid block faced on the rubbing surface if desired with anti-friction metal, but usually in large sizes will comprise end plates and compartments formed by intermediate transverse ribs. Each compartment is then provided with a rubbing block pressed into contact with the internal surface of the cylinder by springs fitted in boxes removably secured to the top of the chair.

Specification of Letters Patent.

Patented July 19, 1921.

serial No. 435,462.

A uniform pressure of predetermined amount per square inch of bearing surface can consequently be exerted on each block, which can move up and down in accommodation with any diamctral or lineal variations of the cylinder at diferent parts of its length.

Springs are also provided in one piston part by which pressure is exerted on one end of the chair to bed the other end Atace against the inner face of the other piston part. These springs allow for any variations in the length of the chair or in the varying distance apart of the two parts of the piston.

In the accompanying drawing, which represents an example oli. a construction according to the invention, Figure l is a longitudinal section through the cylinder of a uniflow steam cylinder; Fig. 2 a plan oi. the piston and chair with parts removed; F E3 is a transverse section o the cylinder on the line 3-3 of Fig. 1.

A is the cylinder, B', B2 the two parts oi the piston which are exposed to steam pressure only on their outer surfaces. The parte B', B2 are secured to a rod C which maintains them at the required distance apart by nuts D', D2 which may be constructed in any known manner engaging with threaded parts of the rod and adapted to ftorce the preferably beveled hubs of the parts B', B2 into close contact with correspondingly beveled sides of collars E', E2 provided on the rod C. Keys F', F2 secure the pistons against rotatlonal displacement relatively to the rods.

As the steam pressure acts always in one direction, any tendency to displace the pistons on the rod C is resisted by the collars E', E2 and is not borne by the nuts D', D2 which are therefore not liable to work loose.

Light steel plates G", G2 are bolted to the inner surfaces of the piston in order to prevent the condenser vapors from having direct access to the heated space in the interior of the pistons and to retard heat transmission from these spaces to the condenser. In this way a chamber is provided in each piston of which the temperature is intermediate between that of the entering steam and the condenser.

A door H' is provided at the upper part of the -cylinders as described in U. S. A. Specification Ser. No. 243905 by which at any time the condition of the piston and the means for supporting the piston can be examined.

The chair I supporting the weight of the piston is formed with two end plates J, J2 and transverse ribs K dividing the construction in the example shown into six compartments. The chair is fitted under end lugs L', L2 of the piston and in each compartment a block M is pressed into contact with the interior of the cylinder by spiral springs N iitted in boxes O screwed into the top of the chair. These springs are uniform in size and strength and are calculated and adjusted to bear exactly the weight of the pistons, rod and chair. The weight will consequently be distributed uniformly over the individual blocks M which are adapted to rise and fall and accommodate themselves to .any varying diameter or linear irregularity of the cylinder.

Small set screws P are provided to secure the chair to the piston while the parts are being inserted in the cylinder, after which the set screws are removed.

Spiral springs Q are fitted in boxes R screwed into the inner wall of the front part B and exert a longitudinal pressure on the end plate J to maintain the chair always in abutment against the inner wall of the rear part B2. The springs Q are strong enough to maintain the chair in contact with the rear part of the piston against the forces due to inertia, friction or other action tending to displace the chair. The springs Q also provide compensation for the variations of length of the chair and of the rod C, obviate any tendency to jamming7 and prevent the pistons from being strained by changes in the longitudinal dimensions or' the parts.

Having now described the nature of the said invention and the best means l know of carrying the saine into practical eil'ect, l. claim l. A uniliow steam engine piston constructed in two parts, each part being separately secured to a piston rod connnon to each part and in which a, chair or slipper arranged between the two parts of the piston supports the weight of the piston.

2. A piston according to claim l, in which the chair comprises blocks adapted under spring` pressure to make rubbing contact with the internal surface ot the cylinder.

A piston according to claim l, in which the individual blocks are exposed to a uniform spring pressure of predetermined amount per square inch of rubbing surface.

t. A piston according to claim l., in which spring pressure is applied to the chair in the axial direction of the cylinder in order to allow for variations in the length o lE the piston and of the chair.

5. A piston according to claim l, in which each part is heldl against collars on the piston rod by nuts, cotters or the like, which are relieved from the pressure due to the steam load.

6. A piston according to claim l, in which plates are secured to the inner surfaces of each part ot' the piston, sul'istantially as and for the purpose described.

In testimony whereolt I have name to this specification.

HENRY PILLNG.

signed my VIV 

